1. Field of the Invention
The present embodiments relate to a method of descaling a mask, and more particularly, to a method of descaling a mask that quickly and effectively removes material attached to the mask.
2. Description of the Related Art
Electroluminescence display devices as emissive type display devices are expected to be next generation display devices due to their wide viewing angles, high contrast, and high response speed.
Electroluminescence display devices are classified as organic light emitting display devices and inorganic light emitting display devices according to material that forms the emission layer (EML) included therein. In particular, organic light emitting display devices are brighter, and have higher driving voltage and higher response speed than inorganic light emitting display devices and can display color images.
An organic light emitting diode (OLED), which is an organic light emitting display device, includes an interlayer located between electrodes facing each other. The interlayer can consist of a variety of layers, e.g., a Hole Injection Layer (HIL), a Hole Transport Layer (HTL), an EML, an Electron Transport Layer (ETL), an Electron Injection Layer (EIL), and the like. Such layers of the organic light emitting device are organic thin films.
Organic thin films such as the HIL, HTL, EML, ETL, EIL, and the like can be formed on a substrate using a deposition method in a deposition apparatus when fabricating the OLED.
Using the deposition method, a thin film is fabricated on a substrate in a vacuum chamber by heating a heating a crucible containing a material to be deposited, and evaporating or sublimating the material to be deposited.
The organic material forming the thin film of the OLED is evaporated or sublimated within a temperature range of from about 250° C. to about 450° C. and a degree of vacuum of from about 10−6 to about 10−7 torr.
Electroluminescence display devices include electrodes facing each other. In particular, an active drive type electroluminescence display device includes thin film transistors having electrodes made of metal, so that such electrodes can be formed using a deposition method.
An electrode material usually evaporates at a temperature higher than the evaporating temperature of the organic material. Such an evaporation temperature varies according to the type of electrode material. Commonly used materials such as magnesium (Mg) and silver (Ag) evaporate at temperatures higher than from about 500° C. to about 600° C., and about 1000° C., respectively. Aluminum (Al) used as the electrode material and lithium (Li) evaporates at temperatures of about 1000° C. and about 300° C., respectively.
A mask is used to form an organic film or a metal film using the deposition method so that the organic film or the metal film can have a specific pattern. To be more specific, a mask having a slit with a predetermined pattern is formed and the organic film or the metal film is deposited through the slit in a desired pattern.
The mask is removed after completing the deposition, in which the organic film or the metal film is necessarily attached to the mask. Such material attached to the mask needs to be removed in order to recycle the removed mask.
Conventionally, an organic solvent is used to remove the material attached to the mask after the deposition. That is, the material attached to the mask is removed by immersing the mask in an organic solvent such as acetone. However, the mask must be immersed in the organic solvent for at least 48 hours in order to remove the material attached to the mask. Therefore, a lot of masks are required for mass production in turn, causing an increase in production costs.